The present invention relates to a garage door assembly. More particularly, the present invention relates to a bottom bracket having a slidable roller housing for an upward acting or vertical opening sectional garage door or single panel garage door.
One problem associated with lightweight and heavy doors constructed of sheet metal, extruded aluminum, as well as polymer materials, has been the provision of suitable brackets for transferring loads from door counterbalance or lifting cables to the door structure itself. A particular problem has been the lowermost bracket for guiding the door for movement between open and closed positions. Desirably, the brackets should be arranged in such a way as to minimize inadvertent disconnection of the bracket from the door when the door counterbalance or lifting cables are under high tension, so as to minimize the chance of injury, damage to the door structure and/or damage to the counterbalance mechanism.
A conventional bottom bracket generally includes a cable attachment and a roller housing for securing a guide member therein. The roller housing typically includes spaced apart flanges stamped out of the bottom bracket, each flange having at least one hole dimensioned to receive a shaft of a roller of the guide member. The flanges of the roller housing are typically positioned on the bottom bracket at a predetermined distance from a side edge and a bottom edge of the bottom bracket. This distance varies when different sized roller diameters (generally 2″ or 3″ diameters depending on the size of tracks of the garage door) are used.
In some cases the flange holes for the roller shaft are slightly larger than the roller shaft such that an end of the shaft can slip out of one of the flange holes. This slippage can prevent the roller shaft from floating sideways in the roller housing during movement of the door thereby causing the roller to bind in between the roller flanges. In these instances, a tube, typically formed of sheet metal, can be inserted through the holes. The roller shaft is then inserted in the tube. A roller with a longer shaft can be used with or without a tube to prevent the roller shaft from slipping out of the flange holes or the tube.
Recently, bottom brackets have included separate U-shaped roller housings. The U-shaped roller housing is generally fastened, such as by a rivet or screw, to a surface of the bottom bracket. Each arm of the U-shaped roller housing includes a pair of holes for either a 2″ roller or a 3″ roller. Because the holes are so close to each other, insert tubes for roller shafts generally can not be used.
On problem associated with the fastening of the U-shaped roller housing to the bottom bracket is that screws can loosen, which can cause the roller housing to disengage from the bottom bracket. With a riveted roller housing, in order to remove or replace the guide member, the entire bottom bracket has to be removed. Because of the tremendous tension and pressure transferred to the cables from the lifting mechanism, the removal of the bottom bracket, which is attached to the cables, can be dangerous. In addition, it is very time consuming to release the pressure from the lifting mechanism just to replace a guide member. Another method in replacing the guide member without having to remove the entire bottom bracket is to bend the door track channel outward and force the roller out of the track. The door panel is then pulled out of its operating position in order to replace the roller. However, this pulling method can be cumbersome when the door track channel is secured to a steel frame or is installed too close to the garage door structure.
Accordingly, there is a need for a new and improved bottom bracket which overcomes certain difficulties and safety issues with the prior art designs while providing better and more advantageous overall results.